An increasing number of deployed radio access networks are based on different radio access technologies (RATs). The availability of multiple access alternatives offers the flexibility of using different RATs and the capability of increasing the overall transmission capacity, providing better service quality and reducing the deployment costs for wireless access. In the future, a mixture of heterogeneous radio technologies will be available. Presently, mobile terminals have the capability for versatile usage of radio communication resources, for example EGSM/HSPA/WLAN/BT/etc. This multi-radio access situation opens the potential to provide access to any network in an “always best connected” fashion. Certain considerations involve utilizing several access techniques simultaneously. In certain considerations they do not even have to be provided by the same network operator.
Multi-radio access technologies have been given a lot of emphasis recently. A modern base station platform expands its supported technologies to cover GSM/EDGE, WCDMA/HSPA and LTE—all running concurrently in a single unit. It supports a multi-radio access technology in order to meet the needs of new and existing 2G and 3G operators who can use their existing infrastructure to deploy new network-wide technologies via simple software upgrade to 3G or LTE.
A general problem is how a user data packet or flow can be transmitted more efficiently in a multi-radio access environment. Different integration options have been identified which provide different capabilities with respect to interworking scenarios and requirements. Coupling between multiple RATs refers to the extent of co-ordination and collaboration across different radio access technologies. The purpose for such collaboration is ultimately the enhancement of the user experience given the QoS requirements and constraints on available radio resources.